Collagen is a major structural protein of connective tissue such as skin, tendon, cartilage and bone. Type 1 collagen forms the major portion of collagen of both soft (skin, tendon) and hard (bone, dentine) connective tissue. Collagen is typically extracted from the skin of animals, such as rat and rabbit. The collagen that is extracted can be used as a coating to new materials or incorporated in a material so as to make the material more biocompatible. Because of its good mechanical properties, biocompatibility, biodegradability, bioavailability, its action on cell development, and hemostatic power, collagen has been used in many medical, veterinary, cosmetic, food, pharmaceutical, biomedical, biotechnological, dental, surgical, dermatological, neurological, orthopedic, ophthalmic, urological and vascular applications. For example, collagen has been used in implants, transplants, organ replacements, tissue equivalents, arterial vessel replacements, hemostatic agents, drug delivery matrices, endodontic therapy, cell culture supports, vitreous replacements, plastic, reconstructive and cosmetic surgery, surgical sutures and surgical dressings.
Various methods have been used for extracting and purifying collagen. Existing methods of collagen extraction and purification typically include extraction from animals using multi-step chemical and mechanical processes, such as described in Ehrmann, R. L., and Gay, G. O., National Cancer Inst. J. 16:1374-1403 and Bornstein, M. B., Lab. Invest, 7:134-137, 1958.
Such methods typically include chemical washes and extractions, filtering, vacuum filtration, decantation, enzyme extraction, salt precipitation, crosslinking reactions and dialysis.
Conventional processes for extracting and purifying collagen, are typically complex, costly and suffer from the disadvantage that the structure of collagen can be modified/denatured by the process. Collagen undergoes glass transition at temperatures as low as 50-60° and if the chemical process used causes the collagen to pass through this glass transition, the physical structure of the collagen can be disrupted. In addition, many extraction methods involve the use of an alkaline metal/metal salt or sodium acetate/hydroxide to precipitate the collagen. Such agents are harsh agents and may cause modification or damage of the collagen. Alternative processes use proteases or enzymes to digest collagen. Proteases and enzymes are typically expensive and can result in alteration and damage to the collagen.
Accordingly, there is a need to provide a simpler method for extracting and purifying collagen.